An antibody discovered by Amgen Inc. (AMGN) researchers reduces weight and increases glucose tolerance in monkeys, according to a study, potentially opening up a new approach for treating obesity and diabetes in humans. The obese monkeys lost about 10 percent of their body weight during the 11-week trial, according to the study, which was paid for by Amgen and published today by the journal Science Translational Medicine. The drug also lowered insulin, glucose and triglyceride levels. “This type of antibody has not been described before,” Yang Li, an author of the study and scientific director at Thousand Oaks, California-based Amgen, said in an interview. “The significance of the antibody, even just finding it, expands our view of what antibodies could potentially do.” The antibody mimics a metabolic hormone naturally produced in humans called Fibroblast growth factor 21. FGF21, which regulates glucose and lipid metabolism, has also been called the “starvation hormone” because it’s secreted by the liver during fasting. A separate study by researchers at the University of Texas Southwestern Medical Center in Dallas found that mice bred to overproduce FGF21 received the benefits of dieting without having to diet. They also lived 30 percent to 40 percent longer than their peers who weren’t genetically modified. A side effect was a loss in bone density.